The idea is that if you're doing most operations with the "foo" table, you'll get much better performance without a variable width column (varchar, text, etc).

They used a table with a varchar(1) column, and got a massive performance hit, but only when the number of columns was large. I'd like to experiment to see if it is the number or pure width of the columns. (In short, compare something like 99xchar(3)+1 varchar(1), or 1xchar(297) + 1 varchar(1).